Modern, fully or at least partially, electrically operated motor vehicles have a rechargeable battery and also one or more electric drives. In this case, electrical energy is provided by the battery. This electrical energy is supplied to a converter which converts the battery voltage into a single- or polyphase voltage for the connected electric drive or drives.
In order to recharge the battery, the vehicle has to be connected to an external supply network, for example the local electricity supply system. In this case, the electric vehicle is intended to be connected to the supply network by means of a connection which is as simple and flexible as possible. Furthermore, the battery is intended to be charged with a power which is as high as possible, in order to keep the charging time as low as possible.
DE 10 2008 063 465 A1 describes an electrically operated vehicle in which a converter circuit for driving the electric drives is also used at the same time as a drive circuit for recharging the vehicle battery. To this end, the electric drive is disconnected from the converter circuit and the converter circuit is connected to the supply network in order to recharge the battery.
During recharging of a battery of an electrically operated vehicle, the converter circuit, which supplies the electrical energy from the supply network to the battery, is operated at a high-frequency clock rate in the range of several kilohertz, usually in the range of between 10 and 30 kHz. Interference signals which can be transmitted into the connected supply network are produced in the process. In order to prevent the connected supply network from being adversely affected, reactions of the charging circuit on the supply network must not exceed prespecified limit values. To this end, the charging circuit has to be equipped with a suitable interference suppression device. On account of the high currents which flow during recharging of the motor vehicle battery, the required interference-suppression means is of very complicated configuration.
There is therefore a need for improved compensation of the interference signals which are produced during charging of a battery of a motor vehicle.